1. Field of the Invention
This invention relates to a universal tool for ejecting the waste from a blanking press for cutting out sheet elements, particularly elements such as paper or cardboard intended for the production of packaging.
2. Related Art
Generally, these blanking presses comprise a plurality of stations disposed one after the other, more particularly a feeder for supplying the machine with sheets of cardboard, and in some constructions a feed table arranging said sheets in layers, a platen press for cutting the sheets one by one to a given shape to produce box blanks, an ejection station removing the unwanted waste resulting from the cutting operation, and finally a station for receiving the resulting blanks in stacks.
It is in the waste ejection station of the blanking press that the tool of this invention is used. The sheet elements processed by such machines each comprise a plurality of blanks which represent the shapes and developed surfaces of the packages made. Although these blanks are carefully disposed and arranged on the surface offered by the sheet in order to obtain optimum utilisation thereof, it is generally not possible to avoid interstitial zones of waste between the blanks resulting mainly from their specific shapes. It is these interstitial surfaces which form the unwanted waste which should be removed from the sheet.
To this end, once a sheet has been cut it is deposited on a perforate plate, a bottom ejection plate, comprising a plurality of openings. These openings are situated in register with the waste from the sheet and have a shape corresponding to such waste. Each waste item can be removed by clamping between two ejection needles mounted respectively on a top movable tool and the other telescopic needles on a bottom tool. In a vertical movement, these two tools in one operation remove all the waste from the sheet. An ejection station of this kind is described in greater detail in U.S. Pat. No. 3,786,731.
More simply, the waste ejection station can comprise just a single movable top tool pushing the waste through the perforate plate.
One method of making the ejection tool comprises using a flat surface, generally a wooden board, in which ejection needles are fixed at locations corresponding to the waste for ejection, said ejection needles simply being types of nail which have been nailed into the wooden board. Although appearing to be very economical, this solution becomes complex and soon becomes tedious when the machine has to be prepared for all kinds of different jobs each requiring a specific tool, in order to meet customer requirements.
Another embodiment of the ejection tool comprises using needles which can be adjustably fixed in order to allow more readily for a complete range of different jobs. To this end, the tool in question comprises a rectangular frame and cross-members connecting the side or longitudinal bars of the frame, so that said cross-members, serving as a support for the ejection needles, can be positioned at the locations of the waste for ejection. Each ejection needle must be screwed on a radially adjustable support which can turn through a 360xc2x0 periphery in order to be able to be properly positioned with respect to the waste for ejection. This embodiment has the disadvantage of requiring, for each ejection needle, assembly and adjustment of a number of parts making up its support. Also, since the blanking press can carry out different jobs corresponding to a number of types and formats of blanks, the complicated adjustment of the position of the ejection tools depending on the required job has to be repeated each time. Although this tool has the advantage of being adaptable to any job and having just one and the same batch of parts, the positioning of the ejection needles is on the other hand an adjustment task which may be long and laborious depending on the complexity of the boxes to be cut and the waste they produce. Finally, the size, and particularly the relatively high cost price of this type of tool, necessitates rational utilisation of the system; for this reason, these ejection tools are generally dismantled after each job and re-assembled in a new configuration for a new job, and this obviously takes up an appreciable amount of time which is not compatible with the required production needs.
Another possible solution is not to separate the waste during production but to carry out the operation manually when removing the processed product delivered by the platen press. This solution, which is very restrictive for medium and large runs, is economically inconceivable in industrialised countries for obvious labour cost reasons. Also, the time required for this task would be totally disproportionate to the time taken by a machine to produce the required product in one operation. Finally, manual removal of the waste gives rise to different problems, such as the risk of tearing, risk of unwanted separation of processed blanks, problems associated with handling stacks of sheets, and finally hygiene problems for sheets intended for packing medical or food products.
The object of this invention is to obviate these disadvantages by providing a universal ejection tool which, above all, is economic and which is of simple design while remaining effective and reliable. It must also be capable of ejecting any type of waste no matter where over the entire extent of the sheet and be suitable for jobs covering the entire range of sheet formats which it is possible to produce with the type of platen press for which the ejection tool in question is provided. The time required for preparation of this tool for a given job must be as short as possible. This ejection tool must also significantly reduce the number of operations and spare parts involved in the tool preparation stage, and must offer manifest convenience in the case of adding, removing or moving one or more of the means providing the waste ejection.
To this end, the invention relates to an ejection tool according to claim 1.